Precious metal powder, such as silver powder, is used in the electronics industry for the manufacture of conductive pastes. The conductive pastes are screen printed onto substrates forming conductive circuit patterns. These circuits are then dried and fired to volatilize and burn out the liquid organic medium and sinter the metal particles.
Capital investment for the furnace can be decreased when precious metals such as gold, silver, and palladium are used as the conductor because these metals can be fired in air. Using precious metals, however, invites a sharp rise in material costs because precious metals are expensive.
Copper is widely used as a conductive component in semiconductor circuits and the like. Copper has the advantage of being less expensive than silver and other precious metals. However, copper cannot be fired in air because it oxidizes easily, and this increases capital investment because firing under a nitrogen atmosphere and the like is required.
Thus, in the process of forming an electrode using a conductive paste, the development of technology is needed that will satisfy the following requirements of: 1) enabling the use of inexpensive copper powder, 2) enabling firing to be performed in air, and 3) achieving low electrode resistance.